Method of making skinless sausage using reusable porous polytetrafluoroethylene casing

Abstract

A reusable tubular casing is made of porous polytetrafluoroethylene (PTFE) membrane for the production of caseless (skinless) parboil or raw sausages. The membrane has a microstructure comprising PTFE nodes connected by PTFE fibrils with a porosity of about 70-80%, a Gurley No. less than about 28 seconds, a Bubble Point Pressure greater than about 13, and a Water Entry Pressure greater than about 40 psig. The casing is contacted on at least a part of its circumferential area by a porous support such as a cylindrical lattice. A new process for production of parboil or raw sausage involves heating the sausage in casing formed by a reusable non-adherent, vapor permeable membrane to drive off moisture and other volatile materials, and removing the sausage from the casing. The sausage can subsequently be smoked and the casing reused.

What is claimed is: 
     
       1. A process for the production of caseless sausages, the process comprising the steps of inserting pliable, reusable porous casings into casing support structures, the pliable casings conforming to the internal cross-sectional shape of the support structures, the reusable tubular casings being formed of a vapor-permeable highly porous polytetrafluoroethylene membrane having a microstructure of nodes interconnected by fibrils, said membrane being heat stable, and non-adherent to bulk sausage; filling the reusable casings with unprocessed sausage material; reddening the sausage material to a desired degree of redness by heating the filled casings; coagulating the bulk sausage material by continued heating of the sausage material, said reddening and coagulating steps including the concurrent steps of venting radially through the porous casing excess steam, water vapor, and other gaseous constituents released by the sausage material during said reddening and coagulating steps; ejecting the coagulated sausage material from the porous casings, the integrity of the membrane being maintained during said ejection step, and the external surface of the ejected sausage being smooth and its integrity being maintained during the ejection step; cleaning said reusable casings for subsequent refill with unprocessed sausage material; and refilling the reusable casings. 
     
     
       2. The process of claim 1 in which the ejection step includes pneumatically ejecting the coagulated sausage material in a substantially axial direction. 
     
     
       3. The process as in claim 1 wherein the casings and the casing support structures are non-metallic, and said reddening and coagulating steps include the step of irradiating the casing and contained sausage material with microwaves. 
     
     
       4. The process as in claim 1 wherein said cleaning step includes the step of exposing the casings to ultrasonic waves. 
     
     
       5. The process as in claim 1 further including the step of pre-reddening the unprocessed sausage material to less than the desired degree of redness, said pre-reddening step occurring prior to the filling step. 
     
     
       6. The process as in claim 1 for making parboil sausages, wherein the reddening step includes heating the filled casings to a temperature of about 35° C. and the coagulating step includes heating the sausage material to about 80° C. 
     
     
       7. The process as in claim 1 further including the step of smoking the coagulated sausage material after the ejecting step.